New Nanostructured Cellulose Materials for the Filtration of Pollutants and for the Adsorption of Dyes

摘要

The production of functionalized cotton materials of large use (gauze and sanitary cotton) has been worked up, in order to adsorb polluting substances and dyes from aqueous solutions. Glycidyl methacrylate (GMA) has been used as functionalizing agent. C1 and C3 were produced by Fenton reaction, while C2 and C4 by electron beam (EB) irradiation (Scheme 1). C1 and C2 bear hydrophobic branches, ending with the glycidyl group, on the cellulose surface, while the cellulose surface of C3 and C4 is made more hydrophilic by appendages ending with the glycerol group. Aromatic polluting substances like phenol, 4-nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol (picric acid) and 2-naphtol were all tested with C1 and C3 in gauze form. Phenol was not adsorbed at all. The three nitrophenols have shown different adsorption properties towards C1 and C3, in function of the pH. In particular, C3 shows the best removing performances of nitrophenols in basic water. 2-Naphtol was efficiently adsorbed by C1 and, even if in a less efficient way, also by C3. On the base of these results, many factors, like the size of the aromatic molecules, their polarity and their acidity, seem to play a role in the efficiency and in the mechanism of the adsorption process. C1 shows better affinity towards less polar molecules, while C3 has better performances towards more polar molecules. The murexide dye has been tested with C2 and C4, in gauze and sanitary cotton forms. It has been adsorbed only by C4, confirming that the presence of hydrophilic appendages on the cellulose surface is fundamental for the filter efficiency towards polar molecules.